Protecting telecommunications equipment in telephone central offices or other locations against sneak currents and voltage surges is well known. Traditional protectors include carbon blocks and gas tubes. These protectors, however, have a wide spread in voltage breakdown levels and large variability with surge rise time. The life, furthermore, of a carbon block is limited. Gas tubes and carbon blocks protect either tip conductor or ring conductor but not balanced protection on both.
The problems with gas tubes and carbon blocks have been solved by using solid state devices. Solid state protectors have instantaneous response for all surges, longer life and provides balanced protection on both tip and ring for high voltages on either tip or ring. An example of a circuit for balanced protection is shown in U.S. Pat. No. 4,408,248 issued Oct. 4, 1983 to R. M. Bulley et al. An example of a solid state protector circuit is disclosed in U.S. Pat. No. 4,322,767 issued Mar. 30, 1982 to M. A. El Hamamsy et al. Solid state protectors would become practical if they were made to fit within substantially the same space occupied by a pair of traditional carbon blocks and gas tubes.